Power transmission mechanism for aircraft engines



June 4, 1946. P. E. MERCIER I 2,401,355

POWER TRANSMISSION MECHANISM FOR AIRCRAFTENGINES Filed Aug. 10, 1943 2 Sheets-Sheet 1 A INVENTOR `Fume 4, 1946. P. E. MERCIER 2,401,365

POWER TRANSMISSION MECHANISM FOR AIRCRAFT ENGINES Filed Aug. v1o, 194s 2 sheets-sheet 2 ATTORNEYS may be divided roughly into' two types.

l of either propeller.

Patented June 4, 1946 POWER TRANSMISSION MECHANISM FOR AIRCRAFT ENGINES Pierre Ernest Mercier, New York, N. Y., assignor to Stratos Corporation, Farmingdale, N. Y., a corporation'oi' Delaware Application August 410, 1943, Serial No. 498,034 1o claims. Eloi. 12s-171) My present invention relates to power transmission mechanisms for aircraft engines and comprisesimproved mechanical means for driving aircraft accessories such as the supercharger, the blower for delivering cooling air to the' engine and the like. More particularly the invention comprises means for obtaining any desired relation between the speed of the engine shaft and theV rotating speed o f accessories driven thereby and for continuously changing suchrelation within reasonable limits in accordance with the altitude of flight and the power developed by the engine.

Known transmission mechanisms for drivingA counterrotating propellers from the engine shaft In one type of mechanism the rotating speed of each propeller necessarily bears a fixed ratio to the engine speed. In the other type of known mechanism, and that with which the present invention is concerned, lthere is no such fixed ratio between the rotating speed of either propeller and that of the engine. Suchv latter type of mechanism may include two gear assemblies having a common part moving freely to apportion the respective torques applied to the propeller shafts; when such gear assemblies are symmetrical thev respecn tive torques applied to the propeller shafts are equal. metrical the ratio' of the respective torques applied to the propeller` shafts is not equal to one Ibut is invariable'ior any given mechanism.

In accordance with the present invention an auxiliary shaft of an airplane accessory is so connected to mechnism of the above mentioned second type that the rotating speed of the auxillary shaft is a predetermined function of the rotating speeds of the propellers.

Thisarrangement permits of a great flexibility of the control of the rotating speed of the supercharger or other accessory relative to the engine speed as will be readily apparent, as, where controllable pitch propellers are employed, the pitch` When such gear assemblies are unsymof one propeller may be controlled from the engine speed while the control of the pitch of the other propeller may be utilized for adjustment of the relation between the rotating speed of the connected in accordance with the invention is of the type wherein there is no xed ratio between the rotating speed of the engine shaft and that Where such mechanism includes two gear assemblies, then because of the torque applied to the auxiliary shaft or shafts in the new arrangements, such gear assemblies are preferably asymmetricalon order to equalize the respective'torques applied to the propeller shafts -for certain conditions and'values of the power taken by the auxiliary shaft.

It is also'possible, by the mechanisms hereinafter described, that power maybe delivered to the propeller system from the auxiliary shaft so as to supplement'l the power delivered by the engine. In this case, of course, the supercharger or other accessory would be driven by the exhaust turbine or other source of energy and thel auxiliary shaft would be driven by the excess of energy available from such source over that required for the accessory. Y

The connection of the auxiliary shaft or shafts to the propeller reduction gear system' of the propellers may be effected in various ways, depending upon the particular relations desired. For example, the connection may be such that the rotating speed of the auxiliary shaft will bear a fixed ratio to the rotating speed of one propeller shaft, or to the difference of the absolute speeds of the two propellers, or the rotating speed of the auxiliary shaft may be made equal to the di'erence between, or to the sum of, values each proportional to the speed of a different one of the two propellers or equal to the difference between, or to the sum of, values proportional respectively to the speed of one propeller and to the speed of engine shaft.

Thesevarious arrangements and the particular advantages of each will be better understood `from the following description and by reference to the accompanying drawings, of which:

Fig. 1 is a. side view partly in section f an airplane engine and supercharger therefor driven by an auxiliary shaft; the shaft being connected `to the propeller gear reduction system in accordance with any one of the arrangements of Figs. 2 to 5.

Fig.. 2 is a longitudinal sectional view through mechanism representing one embodiment of the invention wherein the auxiliary shaft is driven at a rotating speed .equal to the difference .between two values respectively proportional to the speeds of the two propellers and suitable for use in the case of an engine of medium power. Fig. 3 is a view similar to Fig. 2 but illustrating another embodiment of the invention wherein the auxiliary shaft is driven at a rotating speed equal to the difference between two values respectively proportional to the speed of one propeller and to the speed of the engine shaft and suitable for use in the case of a high powered engine. i

Fig. 4 is a longitudinal sectional view of mecha- 4 nisin representing another embodiment of the invention wherein two auxiliaries are so driven from the propeller reduction gearing as to have their rotating speeds proportional to the rotating speed of one of the two propellers; and l Fig. 5 is a view similar to that of Fig. 4'wherein the rotating speeds of the auxiliaries are proportional to the arithmetlcal dierence of the speeds of the two propellers.

In Fig. 1 two adjustable pitch counterrotating with the crown I.

spectively on internal shaft II and external shaft I'I, both shafts being driven by a radial engine |03. A supercharger |05, here shown as of the centrifugal type, receives air through the inlet pipe |06 and delivers it to the engine inlet manifold through the diil'users |01, scroll |08 and conduit |09. The shaft IIO of the supercharger carries a pinion III geared to satellites I|2 carried on axles I I3 and meshing with a'n internal xed gear III. The axles II3 are secured to a carrier II3a integral with a crown toothed gear II5 rotatably mounted on the shaft I and driven from a bevel gear IIS on a shaft II1. Shaft II1, by means of conical gears II8 and H0, is driven by the auxiliary shaft I 6. In accordance with the invention, auxiliary shaft I6 is connected to the propeller reduction gearvmechanism within the crank case I0 in such manner Vthat the rotating .speed of the shaft is a function of the rotating speed of the propellers. Connections of the shaft A in Fig. 2 the engine shaft |00 has a crown I se cured thereto with an internal gear 2 geared with satellites 3. 'Ihe satellites 3 turn on axles 4 carried by a member 5 which also carries axles B of Isatellites 1 geared to an internal gear 8 integral The satellites 3 are. on the other hand, geared with a central gear 9 carried on a wheel I0 secured tothe shaft II of one propeller. Satellites 1, 'on the other hand, are geared with a central pinion I2 which rotates with a wheel I3 carrying an external gear Il which drives a pinion I5 on the auxiliary shaft I6. Member 5 is fixed to the shaft I1 of the other propeller. A part of the crank case I0 provides a bearing for the end of the auxiliary shaft I0.

In Fig. 2 the rotating speed of auxiliary shaft I6 is equal to the difference between values proportional respectively to the rotating speeds of the propeller shafts II and I1, as can be readily demonstrated.

Let Wr be the rotating speed of the engine shaft |00 and therefore of the internal gears 2 and 0 as well, Wi the rotating speed of the inner propeller shaft II, and therefore of gear 9, and W0 the rotating speed of the outer propeller shaft I1 and therefore of member 5 carriedthereby. We can then write for the gears 2 and 0 and the satel lites 4 wherein f/b is the ratio of the number of teeth of gears 9 and 2 and K is a constant.

Similarly for gears 0 and I2 and satellites 1 we have Where WA is the rotating speed of gear I2 proportional to the rotating speed of the auxiliary shaft I6), f/b is the ratio of the number of teeth of gears `I2 and 8 and K a constant.

From Equations 1 and 2 we have engine.

, 4 and by subtraction W.4-Wi= (K-K') Wo-l-K'WA-KWI from which we obtain y Wf=,-{,l 1[ K-1 W.- KK' W.1 (o

In Equation 5 and in the derivation thereof the symbols We, Wi, W0 and WA for the rotating' speeds are algebraic values. If the direction of rotation of the engine shaft, that is of gear 2, be taken as positive, then that of the outer propeller shaft I1 will likewise be positive while the direction of rotation of the inner propeller shaft II will be negative. On the assumption that the direction of rotation of the auxiliary shaft is the same as that of the inner propeller shaft, and by substitution of the numerical values wx, wi and wo, for the respective algebraic values WA, Wi and W0 with corresponding change of sign of the coeilicient` of the rotating speed of the outer propeller shaft, Equation 5 becomes In Equation 5a both K and K' are always greater than unity. Hence the coefficient of un is positive. Whether the coemcient of wo is positive or negative depends upon the relative magnitude of K and K'. If K is greater than K, that is, if the ratio of the number of teeth of gear 0 to gear I2 is greater than the ratio of the teeth of gear 2 to gear 3, then wn, proportional to the rotating speed of the auxiliary shaft I6, is equal to lthe difference between two. values, respectively proportional to the rotating speeds of the two propeller shafts II and I1, irrespective of what may be the rotating speed of the engine shaft |00. If the first term of Equation 5a is greaterthan the second term, the auxiliary shaft is rotating in the same direction as the inner propeller shaft, whereas if the second term 'exceeds the rst term, then the auxiliary shaft rotates in the same direction as the outer propeller shaft. If K' is less than K, then wA is'equal to the sum of two values respectively proportional to the rotating speeds of the two propeller shafts. The auxiliary shaft I0 may drive the engine supercharger as shown in Fig. 1, and, lif desired, it may drive in parallel therewith a blower for supplying cooling air to the Since the multiplication gear system for the supercharger may be arbitrarily selected, it is obvious that by adjusting the respective pitches of the two propellers the mechanism of Fig. 2

external propeller shaft I1 is greater than that applied to the internal shaft II. The arrangement of Fig. 2 is particularly suitable for use with an aircraft engine of medium power.

In the embodiment of the invention illustrated in Fig. 3 the engine shaft |00 carries a wheel 22 whichbears an external gear 22 meshing with satellites 25. A member 24 carrying'the axles for the satellites 25 rotates with the internal propeller shaft I| centered in the engine shaft |00 by the bearing 21. An internal gear 20 meshing cording to the multiplication gear system driven with the satellites es, 'is' attached to a member 29 which rotates with the ,outer propeller shaft Il.Y

A member 35, integral with member 29, carries an internal gear 3l.' Gear 3l drives satellites 32, 'whose axles are-attached to an annular memberl 33 which drives `a wheel 34 bearings. gear 35.-

Satellites 32'mesh with a c entral gear 35 carried by the engine shaft |00. Gear drives the pinion i5 on the auxiliary shaft' |5.- As in Figs. 1

and 2. a part of the crankc'ase I8 encloses the gear mechanism and carries bearings for the propeller i shaft il and the auxiliary shaft IB.

.` vWith the mechanism of Fig. 3, the rotating speed of the auxiliary shaft i6 will be equal to the difference between, or to the sum of, values,

proportional respectively to the rotating speeds of the inner propeller shaft l i and the engine shaft l'as can be readily demonstrated.

As before, if WE is the rotating speed of the engine shaft ldd-'and therefore of gears 23 and 35, Wo the rotating speed ofthe outer propeller shaft il, and therefore of gears 28 and 3|, and Wi the .rotating speed of the inner propeller shaft il and therefore of member 24 carrying the-satellites 25.r a

where WA is the rotating speed of wheel 34 and vthereforeproportional to the rotating'speed of the auxiliary shaft it. From Equations 7 and 8 we have r Taking., as before, the direction of rotation of the engine shaft, that is, of gear 23 as positivej then the direction of rotation ofthe innerpropeller shaft il is positive and of the outer pro- `peller shaft l1 is negative. Assuming the direction of the auxiliary shaft the same as the engine shaft, then the algebraic Equation 9 becomes wt: 4KI 5?? As in the embodiment of the inventionillus# trated in Fig. 1 the auxiliary shaft i5 maydrive the supercharger andmay also drive another aircraft accessory in parallel.

-35 respects, lparticularly in the means for driving the The speed of the aux' then for gears 23 and 28 and satellites 25,' we

have 'l W0- WE .--wt-K 7) and for gears as and stand satellites az wet W'A-WE- (s) carries a satellite carrier, one satellite 41 of which is shown. The external propeller shaft I1,

which is supported' by ball bearings 48 mounted ,Y

inside the nose of the crankcase hasattached thereto a satellite carrier si, asateiute s2 of which A gears with a xed tooth and crown'gear 53. Satellites 41 and 52 are geared with a double gear 54 freely mounted on the internal propellershaft l I. This double gear 54 carries a cylindrical gear 55 which meshes with a pinion 56 and with a. gear 51.

Pinion 55, through a shaft and a pinion 58, drives.

agear. 59 and wheel 65. Wheel 60 carries the vanes 6| positioned in the passage for the intake of cooling air for the engine. Gear 51 is fixed on the auxiliary shaft I6. Thus the gear 54 drives the blower, comprising the vanes 6| `and the shaftl i6 in parallel. Shaft I6 as shown in Fig. 1 drives.

the supercharger for the engine.

That the rotating speed of the auxiliary shaft I5 will be maintained proportional to the rotating speed of the external propeller shaft l1 in the mechanism of Fig. i will be apparent when' the case of zero rotating speed of shaft il is con' sidered. If such speed is zero, satellites 52 will. gear 55 and consev bestationary, as will doubler quently gear i1 as well. In Fig. 4 the control of the rotating speed of the auxiliary shaft l5 is obtainedfor any given speed of the engine shaft, through adjustment of the pitch of the propeller on shaft Il. Also, the available torque may be adjusted between the blower and supercharger by adjustment of the fixed vanes 64 of the air intake or by other known means for controlling the ow of cooling air.v

As the mechanism of Fig. 5 is similar in many two propeller shafts I I and il, to'that of Fig. 4. the following description will be 'confined to the points of difference. In Fig. 5 the satellite carrier 4B has rigidly secured thereto a crown gear 10 and the satellite carrier 5l similarly has secured thereto a crown gear 1I. These crown gears 10 and 1l mesh with a pinion 12 freely .rotatable on a pin 13'which-rides in a. circumferential groove iliary shaft may be adjusted by 'varying the pitch 1n the emhodimntof' the invention illustratedin Fig. 4 the rotating speed ofthe auxiliary shaft I6 is -maintained proportional to, the rotating speed of the external propellershaft. In'Fig'. 4 the engine shaft I Illl carries a conical toothed crowngear 43. The internal propeller `shaft H iscentered byv bearing in the engine shaft |00 Vand Fig. 3 is preferred to that or in the double gear 54. .The pin 13 carries an anf Anular member 14 provided with anA external gear I5 which meshes with the gear 51 on the auxiliary shaft I8 and with the pinion 56 driving the fan through pinion 58 and gear 59. Thusthe rotating speed of the auxiliary shaft is maintained proportional to the difference in the absolute values of the rotating speeds of the propeller shafts.

The arrangement of 5 allows a wide variation in the working conditions 'of the superchargeror otherV accessory drivenby the shaft iB 'since with proper multiplication gearing a small difference between the rotatingl speeds of the pro-v peller shafts may induce a great variation in the i corresponding rotating speed of the auxiliary shaft. As in the other embodiments of the invention, the control of the rotating speed of the tained, for any given speed of the engine, through the proper adjustment of the pitch of the propellers. Thus the mechanisms of Figs. 4 and 5 might be considered theoretically as special cases. of the mechanism of Fig. 2.- That is,1lg. 4 corresponds to the case when the coefficient of Wi of Equa tion 5 equals zero, and Fig. 5 corresponds to the casewhen the coefclents of Wi and Wo of Equai tion 5 are equal. In such special cases the rotating speed of the auxiliary shaft can berindependen t of the engine speed. `.luittntlly these special anism of Fig. 2.

The invention has now been described in connection with several embodiments thereof, in each of which an auxiliary shaft is connected with the propeller reduction gearing so as to be driven thereby and so as to have its rotating speed varied by adjustment of the pitch of one or of both propellers. In -each embodiment of the invention the rotating speed of the auxiliary shaft is a predetermined function of the rotating speeds of the two propellers. As heretofore indicated, mechanisms constructed according to the invention are primarily intended for obtaining any desired relation between the rotating 'speed of the supercharger and of the engine, but such application of the invention, although at the present time probably of the most immediate utility, is not the only application to which the invention may be put. As exhaust turbines adapted to withstand higher and higher temperatures are developed, more and more power will become available therefrom and such power can be used to drive the supercharger and the excess thereof over that required for this purpose could be applied to an auxiliary shaft such as shaft I6. Shaft I6 would then deliver power to the propellers, thus supplementing that delivered by the engine.

It will be understood that the invention in its broadest scope is not limited to the specific mechanisms illustrated in the drawings except as dened in the 'appended claims.

I claim:

1. The combination according to claim 7 wherein said reduction mechanism comprises a crown 4 secured to the engine shaft and carrying an internal gear, an external gear secured to one propeller shaft, a satellite carrying member secured to 4the other propeller shaft, satellites carried thereby and engaging said external and internal gears. a second internal gear carried by said crown, an external gear rotatably mounted on a. propeller shaft, additional satellites carried by said member and engaging said last mentioned internal and external gears, and wherein said ele- `ment comprises la gear wheel secured to said last mentioned external gear.

2. The combination according to claim 'I wherein said reduction mechanism comprises a central gear secured to said engine shaft, an internal gear carried by one propeller shaft. satellites geared to said central and internal gears, a carrier for said satellites secured to the other propeller shaft, a second central gear carried by said engine shaft, a second internal gear carried by said first mentioned propeller shaft, and satellites geared to said last mentioned central and internal gears, and wherein said element comprises a carrier for said last mentioned satellites.

3. In an airplane the combination comprising an engine having a shaft, a pair of coaxial shafts and counter-rotating propellers mounted thereon, an auxiliary shaft and mechanism for the transmission of motion from said engine shafts to said coaxial shafts and to said auxiliary shaft, said mechanism comprising a satellite carrier secured to'each propeller shaft, satellites carried thereby, a double crown gear rotatably mounted von one of the propeller shafts, and

provided with a circumferential groove, the satellites on said carriers engaging said double gear therebetween, a crown gear on the engine shaft engaging the satellite on one carrier and a fixed 'ternal gear.

8v y gear engaging -the satellite on the other carrier, an annular external gear encircling said double gear. a pin carried by said annular gear, slida'ble in said groove, a pinion rotatably mountedon saidpin,l annular crown gears fixed to said carriers and engaging said pinion therebetween, and a gear on said auxiliary shaft engaging said ex- 4. The combination according'to claim 3 including a supercharger for the engine driven by said auxiliary shaft, a. blower for delivering cool-- ing air to the engine and means for driving said blower from said external gear.

-5. In'an airplane, a pair of controllable pitch counter rotating propellers mounted on coaxial shafts', an engine having a shaft, reduction mechanism for driving thepropeller shafts from said engine shaft, said mechanism including an element rotating at a speed which is a predetermined function of the rotating speeds of the propellers, a supercharger, an auxiliary shaft for driving said supercharger, and driving connections between said auxiliary shaft and said element whereby the rotating speedof said supercharger may be varied independently of the rotating speed of. the engine shaft by adjustment of the pitch of the propellers.-

6. The combination according to claim 5 including a blower for delivering cooling air to the engine and means for driving said blower in parallel with said auxiliary shaft to divide the available torque therebetween.V

7. 'I'he combination with an airplane engine having a shaft, of la pair of coaxial shafts, controllable pitch propellers mounted on said coaxial shafts, a reduction mechanism intermediate said shafts, a reduction mechanism intermediate said engineshaft and coaxial shafts for driving the propellers in opposite directions from the engine shaft, an element in said mechanism rotating at a speed which for any fixed speed of the engine shaft varies directly with variations in the difference between the absolute rotatingspeeds of the two propellers, an auxiliary shaft coupled to said element so as to be driven thereby Y and a supercharger driven by said auxiliary shaft,

whereby the rotating speed of the supercharger relative to that of the engine may be varied by adjustment of the pitch of a propeller.

9. The combination according to claim 3 wherein said propellers are of the controllable pitchA type and including a supercharger driven by said auxiliary shaft, whereby the yrotating speed of the supercharger relative to that of the engine shaft mayjbe varied by adjustment of the pitch of a propeller.

l0. The combination accordingto claim 'l including a blower driven in parallel with said supercharger by said auxiliary shaft whereby the rotating speeds of the supercharger and blower relative to that of the engine may be varied by adjustment of the pitch of a propeller.

PIERRE ERNEST MERCIER.. 

